User menu

User login

You are here

Primary tabs

example of telescoping sum

Some trigonometric sums, as ∑k=1ncos⁡k⁢αsuperscriptsubscriptk1nkα\sum_{{k=1}}^{n}\cos{k\alpha} and ∑k=1nsin⁡k⁢αsuperscriptsubscriptk1nkα\sum_{{k=1}}^{n}\sin{k\alpha}, may be telescoped if the terms are first edited by a suitable goniometric formula (‘‘product formula’’). E.g. we may write: